Food Service Cabinet With Nanomaterial Coating

ABSTRACT

A food service cabinet is provided with a coating having as an ingredient thereof a nanomaterial. The temperature and humidity of the interior of the food service cabinet can be controlled to keep food at a desired temperature and/or humidity. The coating may be Nansulate™, which includes Hydro-NM-Oxide as a nanomaterial. The coating is hydrophobic and provides thermal insulation, corrosion resistance and mold resistance. According to a method of manufacturing the cabinet having the nanomaterial coating, the coating may be applied by a brush, a roller or an airless sprayer at low pressure, in three coats, each coat being approximately 3-5 wet mils in thickness.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of priority based on U.S. provisional application No. 60/881,194, filed Jan. 19, 2007, which is hereby incorporated by reference herein in its entirety, as if fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a food service container or cabinet provided with a coating including a nanomaterial, and a method of manufacturing the same.

2. Description of the Related Art

Food service cabinets for holding or proofing food are commonly used in the food service industry, e.g., in restaurants, bakeries, and the like. For example, uninsulated holding/proofing cabinets are available from InterMetro Industries Corporation, Wilkes-Barre, Pa., and are identified as the C175 Flavorview™ Series. Such cabinets have the capability of controlling the temperature and/or humidity within the cabinet, in order to keep prepared food hot for serving and/or to provide the necessary heat and humidity for yeast products (breads, rolls, etc.) to rise. Such cabinets may also have guide rails to accommodate trays for holding food that may be slid in and out of the cabinet, a gasketed transparent door for closing the cabinet and permitting visual inspection of the food without disturbing the controlled atmosphere inside the cabinet, and wheels for mobility.

InterMetro Industries also offers insulated holding cabinets, for example such as those identified as the C199 FlavorHold™ Series. Such cabinets have gasketed solid doors and walls formed by spaced wall panels between which fiber glass insulation is disposed.

The current state of the art of such conventional food service cabinets would benefit from improvements in a number of respects. For example, such a food service cabinet may be made of aluminum as a lightweight and inexpensive material. However, in cabinets without special provision of insulation, the insulating properties of a material such as aluminum alone are not ideal. Consequently, such an uninsulated cabinet would suffer from heat loss, resulting in inefficient energy consumption and potentially in deterioration of food quality, e.g., food being served at temperatures lower than desired or yeast products being improperly or incompletely baked so as to adversely affect taste. In addition, less than ideal insulation may result in the exterior surface of the cabinet being hotter than desired to the touch, making the cabinet impractical, especially if it needs to be moved. Thus, it would be desirable to further insulate a cabinet made of a material such as aluminum.

Conventional means of insulation generally function by trapping air to reduce conductive and convective, but not radiative, heat transfer. Such conventional insulators generally also trap moisture, mold, mildew, fungus, dust, and the like, which both reduces their effectiveness and causes other problems such as corrosion and unsanitary conditions. Accordingly, it would be desirable to provide an insulator that is not subject to these drawbacks.

SUMMARY OF THE INVENTION

The present invention addresses the problems of conventional food service cabinets and means of insulation discussed above and provides numerous other improvements over the prior art.

According to a first aspect of the present invention, there is provided a food service container having a coating, wherein the coating comprises a nanomaterial, and wherein the food service container is for keeping food at a desired temperature and/or humidity and/or for preparing food under controlled conditions of temperature and/or humidity.

According to a second aspect of the present invention, the food service container has means for controlling the temperature and/or humidity of the interior of the container.

According to a third aspect of the present invention, nanomaterial coating for the food service container is Nansulate™.

According to a fourth aspect of the present invention, in the food service container the nanomaterial is Hydro-NM-Oxide.

According to a fifth aspect of the present invention, in the food service container the coating provides thermal insulation for the container.

According to a sixth aspect of the present invention, in the food service container the coating has an R-value of at least approximately 10 ft²·° F.·h/Btu.

According to a seventh aspect of the present invention, in the food service container the coating provides corrosion resistance for the container.

According to an eighth aspect of the present invention, in the food service container the coating adheres directly onto the surface of the container, so as to provide resistance to mold.

According to a ninth aspect of the present invention, in the food service container the coating is hydrophobic.

According to a tenth aspect of the present invention, there is provided a method of manufacturing a food service container having a coating, including steps of providing a container to be coated, and applying a coating comprising a nanomaterial to the container, wherein the food service container is for keeping food at a desired temperature and/or humidity and/or for preparing food under controlled conditions of temperature and/or humidity.

According to an eleventh aspect of the present invention, in the method the coating is applied in the form of paint by means of a brush, by means of a roller or by means of an airless sprayer at low pressure.

According to a twelfth aspect of the present invention, in the method three coats of paint are applied in the applying step, each coat being approximately 3-5 wet mils in thickness.

According to further aspects of the present invention, the method according to the tenth aspect is modified in ways comparable to the second through ninth aspects of the invention.

A better understanding of these and other aspects, features, and advantages of the invention may be had by reference to the drawings and to the accompanying description, in which preferred embodiments of the invention are illustrated and described.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows Table 1, which lists R-values per inch of various materials, and Table 2, which lists thermal conductivity of various materials.

FIG. 2 is a perspective view of a food service cabinet showing schematically the application of a coating containing a nanomaterial to the cabinet by means of a sprayer, as an example of a method of producing the cabinet provided with the coating.

FIG. 3 is a further perspective view of the food service cabinet.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An exemplary embodiment of the present invention will be discussed with reference to the accompanying figures. According to the present invention, a food service cabinet is provided with a coating that has as an ingredient thereof a nanomaterial, i.e., a material having specific properties arising from its nanoscale dimensions. (Such a coating may be referred to herein as a nanomaterial coating.) For purposes of explanation, reference will be made to an uninsulated holding/proofing cabinet such as that in the Intermetro Industries C175 Flavorview™ Series. However, the principles of the present invention are equally applicable to cabinets like the InterMetro Industries C199 FlavorHold™ Series insulated cabinets. Another example of a food service cabinet to which the present invention is applicable, is called a “banquet cart” and is described in U.S. Patent Application Publication No. 2006/0032991 (Olson, et al.), which is incorporated herein in its entirety by reference. By using such a coating as a means of primary or supplemental insulation, the problems of conventional means of insulation discussed above are reduced and numerous other improvements over the prior art are provided.

Generally speaking, thermal insulation functions by reducing the rate of heat transfer. Heat transfer occurs in three ways, namely by conduction, convection and radiation. Some materials are good insulators against one type of heat transfer, but poor insulators against another type. Thus, the choice of insulator often depends on what type of heat transfer predominates in the given application. As discussed, conventional means of insulation are typically designed to reduce conduction and convection but not radiation, by means of trapping air.

The nanomaterial coating, which may be a paint, used in the present invention is able to reduce heat transfer of all three types, generally to a greater degree than conventional insulators. In brief, the greater insulating ability of the nanomaterial coating may be explained as follows. Conduction is hindered by the tiny size of the connections between the particles making up the conduction path, and by the fact that the solids that are present consist of very small particles linked in a three-dimensional network with many so-called “dead ends,” such that conductive heat transfer occurs only through a complicated maze, so to speak, and is not very effective. Convection is limited because the gas molecules within the matrix are subject to the Knudsen effect. The so-called “tunnels” are only the size of the mean free path of the particles (the average distance the particle travels between collisions with other particles), so the particles collide with each other as frequently as they collide with the solid network. As a result, convective heat transfer is virtually eliminated.

In this exemplary embodiment, Nansulate™, manufactured by Industrial Nanotech, Inc., is used as the insulating nanomaterial coating. When fully cured (30-60 days after application), Nansulate™ contains approximately 70% Hydro-NM-Oxide and 30% acrylic resin and performance additives. Hydro-NM-Oxide has been documented to be an excellent, and perhaps the best known, insulator, with an R-value per inch of 10 to 13 ft²·° F.·h/Btu and a thermal conductivity of 0.017 W/mk. For the sake of comparison, the R-value per inch and the thermal conductivity for a variety of materials are listed in Tables 1 and 2, respectively, which are shown in FIG. 1.

In a particularly preferred embodiment, Nansulate™ Translucent PT is used as the insulating coating. However, it is understood that other Nansulate™ products may be used in place of or, as appropriate, in addition to Nansulate™ Translucent PT, depending on the particular application, e.g., Nansulate™ Translucent High Heat, Nansulate™ Translucent GP, Nansulate™ HomeProtect Clear Coat, Nansulate™ HomeProtect Interior, Nansulate™ Top Coat™ (finish), and NanoPrime Surface Primer™. (The term Nansulate™ is understood to refer to all the above-mentioned Nansulate™ products.) It is also understood that other nanomaterial coatings having good insulating properties could be used instead of Nansulate™.

As will be understood by reference to the R-value and thermal conductivity of Nansulate™ as discussed above, a food service cabinet coated with Nansulate™ provides greatly enhanced thermal insulation relative to conventional insulated food service cabinets. Not only does the Nansulate™-coated cabinet greatly improve energy efficiency but it also greatly reduces the exterior surface temperature to provide a significantly greater measure of safety and convenience. In addition to the improved insulation, the Nansulate™-coated cabinet provides many other advantages over the prior art.

First, the Nansulate™-coated cabinet minimizes corrosion by virtue of two properties. The first property is that the nanocomposite ingredient in Nansulate™, Hydro-NM-Oxide, is highly hydrophobic. The second property is that the Nansulate™ paint adheres directly onto the substrate, bonding therewith. This prevents the airspace that generally exists between an insulating material and the substrate, where condensation occurs due to the temperature differential between the insulating material and the substrate. Such condensation is a common cause of corrosion of the substrate.

Second, by virtue of these same two (hydrophobic and close adhesive) properties, mold, mildew and fungus may also be prevented, thus tending to keep the Nansulate™-coated cabinet sanitary. Moreover, this is achieved without any adverse side effects, such as would exist with the use of prior art anti-microbial agents or biocides.

Third, and relatedly, the Nansulate™ paint itself is a non-toxic, water based coating, and is non-flammable.

Fourth, the Nansulate™ may be provided as a translucent coating. This permits visual and ultrasound inspections of the substrate, e.g., for maintenance purposes, through the coating. It also eliminates any significant adverse aesthetic effect. If desired, a white top coat of Nansulate™ may be provided, or the Nansulate™ coating may be painted over with a colored paint, preferably a water-based acrylic paint.

Fifth, the Nansulate™ coating is durable. It will not lose insulation value due to moisture, mold or dust.

Sixth, starting with a conventional food service cabinet and Nansulate™ paint, the Nansulate™-coated cabinet is easy to produce because the Nansulate™ paint is easy to apply, with little clean-up required.

Seventh, the Nansulate™-coated cabinet is inexpensive to produce.

Next, a method of manufacturing the Nansulate™-coated cabinet will be described with reference to FIG. 2.

Starting with a conventional food service cabinet and Nansulate™ paint, the Nansulate™-coated cabinet may be made as follows. Prior to application of the Nansulate™ paint to the cabinet, the paint may be mixed using a mixing paddle at slow speed for approximately 1-2 minutes. Care should be taken during mixing not to cause particle shear of the nanocomposite. If necessary for the given application, a slight reduction of the paint may be carried out, using water as a reducer.

Prior to application on a metallic or other non-painted surface, loose contamination should be removed by wire brushing. Dirt, oil, grease, etc. should be removed using a suitable cleaner/degreaser that does not leave a residue and, for metallic surfaces, by rinsing with water. For metallic surfaces, in addition, loose, flaking rust and/or paint should be removed by hand tool or power tool. For painted surfaces, the paint should not be flaking or peeling. Loose dirt, oil, grease, etc. should be removed, and the surface should be abraded prior to application.

The paint may be applied by a brush, a roller or, as schematically depicted in FIG. 2, an airless sprayer 10 at low pressure. While application of the paint is depicted in FIG. 2 to the exterior of the walls of the cabinet, at least in some applications it may be preferable to apply the paint to the interior of the walls of the cabinet, as described in greater detail below. More particularly, application of the paint to the interior, rather than the exterior, of the walls of the cabinet shields the painted surface from mechanical damage that might otherwise occur when the cabinet is in use.

If using an airless sprayer, the equipment preferably has a minimum pump-rated capacity of 1 GPM, utilizing a ½ inch ID hose, such as a Graco Silver Gun (or equivalent) with a 0.025 tip, 5-19 RAC tip. Three separate coats of paint should be applied, and each coat should be approximately 3-5 wet mils in thickness. Cracking, peeling or flaking of the applied paint indicates that the paint was applied in too thick of a coat. Preferably, each coat should be allowed to dry for a minimum of one hour before applying the next coat. After application, clean up is easy, requiring only soap and water.

The full cure time is approximately 30-60 days, depending on climate and humidity. The paint should not go below freezing until cure time of at least 30 days is completed, or cracking and peeling may occur. The paint provides the maximum degree of thermal insulation when fully cured.

The temperature of the substrate to which the paint is applied should be between 40° F. and 212° F. (4° C. to 100° C.). For application to a surface above 125° F. (52° C.) the first coat should be applied as thinly as possible to prevent blistering. Each subsequent coat may be applied more thickly as the first coat will reduce the surface temperature. After being fully cured, Nansulate™ Translucent PT and GP can maintain their integrity between temperatures of −40° F. and 257° F. (−40° C. to 125° C.), and Nansulate™ Translucent High Heat can maintain its integrity between temperatures of −40° F. and 400° F. (−40° C. to 204° C.).

Next, a typical food service cabinet such as an Intermetro Industries C175 Flavorview™ Series cabinet, without regard to the coating, according to the exemplary embodiment will be described with reference to FIG. 3. The food service cabinet 11 comprises side walls 12, a back wall 14, a top wall 16, and a bottom wall 18. A removable, field-reversible door 20 encloses the front of the cabinet. The side, top, and bottom walls, and the door each have an interior and an exterior surface, and they collectively define an enclosure. The insulating paint described in detail above is applied to at least some and preferably all of the walls. Again it may be most desirable to apply the insulating paint to interior surfaces of the walls. Walls 12, 14, 16 and 18 may be made of aluminum and door 20 has an aluminum frame with a full-length, transparent polycarbonate window 22. Door 20 has a magnetic latch that keeps the door closed even in transport, and a mechanical release, such as a pull handle, for easy one-handed opening by right- or left-handed operators. Door hinges 24 have nylon bushings for smooth, quiet operation and reliable long life, and permit door 20 to swing 180°. Door 20 has a continuous gasket preventing heat loss through leakage. Polycarbonate window 22 also conserves energy by permitting visual inspection of the contents without opening cabinet 11. Of course, the door may also be solid being made of aluminum The interior of cabinet 11 has guide rails 26 accommodating sliding trays (not shown) for holding food. The guide rails may be adjustable to accommodate different sizes of trays. Cabinet 11 is provided with casters 28 including brakes for easy mobility.

Cabinet 11 may be a holding cabinet for keeping prepared food hot until served, or a proofing cabinet for providing heat and humidity in controlled amounts for yeast products to rise, or a combination proofing/holding cabinet. Regardless of which type of cabinet 11 is, cabinet 11 has a continuous blower providing forced air circulation to assure uniform temperature and humidity throughout the interior of cabinet 11. Cabinet 11 also includes a water pan, chimney and perforated air duct at the rear for climate control. Heating elements are provided below the water pan and in the air stream. Separate adjustable temperature and humidity thermostats and a digital thermometer and humidity gage are provided in cabinet 11. Control panel 28 is provided on the exterior of cabinet 11 to permit adjustment of the interior atmosphere without having to open cabinet 11 and disturb the interior atmosphere. Control panel 28 is recessed for protection. A drip trough is provided to prevent wet floor conditions. The blower, water pan, chimney, air duct, heating elements, thermostats, thermometer, humidity gage and control panel may all be deemed means for controlling the temperature and/or humidity of the interior of cabinet 11.

An example of a module, called a “high humidity apparatus”, for use with a food service cabinet to which the present invention is applicable, is described in U.S. Pat. No. 6,157,006 (Sickles, et al.), which is incorporated in its entirety herein by reference.

Cabinet 11 typically has an operating range of 80° F.-180° F. as a holding cabinet (1900 watt, 120 VAC, 16 amp, 60 Hz), or 80° F.-120° F. as a proofing cabinet (1350 watts, 120 VAC, 12 amp, 60 Hz), under normal room temperature conditions.

The structural and operational features of the food service cabinet described above can be modified as desired and as appropriate to the given application. Such modifications are known to those of ordinary skill in the art and hence their description will be omitted. The compositional materials of the cabinet, in particular of the surfaces thereof, may be modified so as to optimize performance of the coating, e.g., adhesion, durability, ease of application, cure time, and the like. Again, such modifications are known to those of ordinary skill in the art and hence their description will be omitted.

While the present invention has been designed with a food service cabinet in mind, the present invention is not limited to such or to food service applications, but could be used for other types of containers, in commercial or non-commercial settings. The invention may also be modified to accommodate non-food service applications thereof, along lines discussed above or in any other suitable manner, as will be understood by those of ordinary skill in the art.

One of ordinary skill in the art will realize that modifications and variations, including but not limited to those discussed above, are possible within the spirit and scope of the present invention. The invention is intended to be limited in scope only by the accompanying claims, which should be accorded the broadest interpretation so as to encompass all such modifications, equivalent structures and functions. 

1. A food service container comprising: a plurality of walls defining an enclosure having an interior and an exterior; and a coating comprising a nanomaterial applied to at least a portion of said plurality of walls, wherein said food service container is capable of at least one of (a) keeping food at a desired temperature and/or humidity and (b) preparing food under controlled conditions of temperature and/or humidity.
 2. The food service container according to claim 1, further comprising means for controlling the temperature and/or humidity of the interior of the container.
 3. The food service container according to claim 1, wherein said nanomaterial comprising said coating is Nansulate™.
 4. The food service container according to claim 1, wherein said nanomaterial comprising said coating is Hydro-NM-Oxide.
 5. The food service container according to claim 1, wherein said coating provides thermal insulation for the container.
 6. The food service container according to claim 5, wherein said coating has an R-value of at least approximately 10 ft²·° F.·h/Btu.
 7. The food service container according to claim 1, wherein said coating provides corrosion resistance for the container.
 8. The food service container according to claim 1, wherein each of said plurality of said walls has an interior surface and an exterior surface, said interior surfaces of at least a portion of said walls thereby defining the enclosure, and wherein said coating is adhered directly to the interior surface at least a portion of said plurality of walls.
 9. The food service container according to claim 1, wherein said coating is hydrophobic.
 10. A method of manufacturing an insulated food service container comprising the steps of: providing a container having a plurality of walls defining an enclosure having an interior and an exterior; and applying a coating comprising a nanomaterial to at least a portion of said plurality of walls, wherein the food service container is capable of at least one of (a) keeping food at a desired temperature and/or humidity, and (b) for preparing food under controlled conditions of temperature and/or humidity.
 11. A method of manufacturing a food service container according to claim 10, wherein said applying step comprises applying the coating by means of at least one of (a) a brush, (b) a roller, or (c) an airless sprayer at low pressure.
 12. The method of manufacturing a food service container according to claim 10, wherein said applying step comprises applying three coats of the nanomaterial, each coat being approximately 3-5 wet mils in thickness.
 13. The method of manufacturing a food service container according to claim 10, wherein said applying step comprises applying the coating in the form of Nansulate™.
 14. The method of manufacturing a food service container according to claim 10, wherein said applying step comprises applying the nanomaterial in the form of Hydro-NM-Oxide.
 15. A method of manufacturing a food service container according to claim 10, wherein said applying step comprises applying the coating in the form of thermal insulating nanomaterial.
 16. The method of manufacturing a food service container according to claim 15, wherein the nanomaterial has an R-value of at least approximately 10 ft²·° F.·h/Btu.
 17. The method of manufacturing a food service container according to claim 10, wherein said applying step comprises applying the coating in the form of a corrosion resistant nanomaterial.
 18. The method of manufacturing a food service container according to claim 10, wherein each of said plurality of walls of the container has an interior surface and an exterior surface, the interior surfaces of at least a portion of said walls thereby defining the enclosure; and wherein said applying step comprises applying the coating to adhere directly to the interior surface of at least a portion of the walls.
 19. The method of manufacturing a food service container according to claim 10, wherein said applying step comprises applying the coating in the form of a hydrophobic nanomaterial. 